Formulas
- Ultrafilter on a set
- Stalk (sheaf)
- Stationary phase approximation
- Steinberg group (K-theory)
- Stencil (numerical analysis)
- Stirling number
- Stolz–Cesàro theorem
- Uncertainty theory (Liu)
- Stone's theorem on one-parameter unitary groups
- Lambda calculus
- Stoneham number
- String group
- Structure constants
- Duffin–Schaeffer theorem
- Regular measure